UB USER INSTRUCTIONS ENGLISH 71569247 07-04
Page 27 of 32
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7 FAULTS; CAUSES AND REMEDIES
FAULT SYMPTOM
P u m p o v e r h e a t s a n d s e i z e s
⇓⇓⇓⇓
⇓⇓⇓⇓
B e a r i n g s h a v e s h o r t l i f e
⇓⇓⇓⇓
⇓⇓⇓⇓
P u m p v i b r a t e s o r i s n o i s y
⇓⇓⇓⇓
⇓⇓⇓⇓
M e c h a n i c a l s e a l h a s s h o r t l i f e
⇓⇓⇓⇓
⇓⇓⇓⇓
M e c h a n i c a l s e a l l e a k s e x c e s s i v e l y
⇓⇓⇓⇓
⇓⇓⇓⇓
P u m p r e q u i r e s e x c e s s i v e p o w e r
⇓⇓⇓⇓
⇓⇓⇓⇓
P u m p l o s e s p r i m e a f t e r s t a r t i n g
⇓⇓⇓⇓
⇓⇓⇓⇓
I n s u f f i c i e n t p r e s s u r e d e v e l o p e d
⇓⇓⇓⇓
⇓⇓⇓⇓
I n s u f f i c i e n t c a p a c i t y d e l i v e r e d
⇓⇓⇓⇓
⇓⇓⇓⇓
P u m p d o e s n o t d e l i v e r l i q u i d
⇓⇓⇓⇓
⇓⇓⇓⇓
PROBABLE CAUSES
POSSIBLE REMEDIES
A. SYSTEM TROUBLES
z
z
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Pump not primed.
Check complete filling.
z
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z
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z
Pump or suction pipe not completely filled with
liquid.
Check and complete filling.
z
z
z
z
z
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z
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z
z
z
z
z
z
z
z z
z
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Suction lift too high or level too low.
Check NPSH
A
>NPSH
R
, proper submergence,
losses at strainers and fittings.
z
z
z
z z
z
z
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z
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z
Excessive amount of air or gas in liquid.
Check and purge from pipes.
z
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z
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z
Air or vapour pocket in suction line.
Check suction line design for pockets.
z
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z
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Air leaks into suction line.
Check airtight pipe then joints and gaskets.
z
z
z
z
z
z
z
z
Air leaks into pump through mechanical seal,
sleeve joints, casing joint or pipe lugs.
Check airtight assembly then joints and gaskets.
z
z
z
z
z
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z
z
Foot valve too small.
Investigate replacing the foot valve.
z
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Foot valve partially clogged.
Clean foot valve.
z
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Inlet of suction pipe insufficiently submerged.
Check cut out system design.
z
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z z
z
z
z z
z
z
z
Total head of system higher than differential head
of pump.
Check discharge head and head losses in
discharge pipe at the valve settings. Check back
pressure is not too high.
z
z
z
z
Total head of system lower than pump design
head.
Throttle at discharge valve or ask Flowserve if the
impeller can be trimmed.
z
z
z
z
Specific gravity of liquid different from design.
Consult Flowserve.
z
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z
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z z
z
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z
Viscosity of liquid differs from design.
Consult Flowserve.
z
z
z
z
z
z
z
z
Operation at very low capacity.
Measure value and check minimum permitted.
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z z
z
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Operation at high capacity.
Measure value and check maximum permitted.
B. MECHANICAL TROUBLES
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z z
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z
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z
z
z
Misalignment due to pipe strain.
Check the flange connections and eliminate
strains using elastic couplings or a method
permitted.
z
z
z
z
Improperly designed foundation.
Check setting of baseplate: tighten, adjust, grout
base as required.
z
z
z
z z
z
z
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z
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z
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z
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Shaft bent.
Check shaft runouts within acceptable values.
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z z
z
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Rotating part rubbing on stationary part internally.
Check for signs of this and consult Flowserve if
necessary.
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z
z
z z
z
z
z z
z
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z z
z
z
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z
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Bearings worn
Replace bearings.
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Wearing ring surfaces worn.
Replace worn wear ring/surfaces.
